Abstract
The particle shape of crushed fine aggegates is determined by the type of rock and the crushing equipment used. Any adequate index which indicate the particle shape of fine aggregates has not been found up to now. Therefore, in this country, reduced natural fine aggregates brings wide use of crushed fine aggregate while without the index of particle shape. Here, author have advanced a new method for indicate the particle shape of fine aggregate by solid content ratio measured with shieved particle which all path 2.5mm shieve and retain on 1.2mm shidve. (Here after, this ratio is called as solid content ratio for shape indicator and shortened into M_V). The numerical values of M_V are spreaded from 53% (crushed sand rock) to 65% (fine river sand), but it appears that the M_V is a good indicator of the amount of water used in a unit volume of concrete mix. A relation showing the quantity of water, in case of water cement ratio is 60% and sand aggregate ratio is 43%, for different M_V is given in Fig.1, for both non-airentrained and airentrained concrete, also it is formularized into formula (4). Minimum requirment of fine aggregates without segregation for defferent M_V is given in Fig.(3), and the equation for estimating S/A from M_V is shown as formula (8). Relations between compressive strength and M_V is shown in Fig.(8). The deta generally indicate that the compressive strength is increased by decreasing M_V. However, the elasticity of concrete is decreased by decreasing M_V.
